The present invention relates to a heat-emitting element cooling apparatus for cooling a heat-emitting element such as electronic components, and a heat sink which is employed therein.
A conventional heat-emitting element cooling apparatus receives a heat sink for cooling an electronic component, which emits heat of a high temperature, such as CPU, and other heat-emitting elements in an air channel. In this apparatus, a wind is fed from a fan unit into the air channel, and the electronic components are forcibly cooled down. The heat sink includes a base onto which a heat-emitting element such as CPU to be cooled is to be mounted, and a plurality of radiation fins fixedly provided at the base. Furthermore the fan unit is arranged at a side of the heat sink and feeds air in one direction along the plurality of radiation fins, thereby enhancing heat radiation from the radiation fins.
U.S. Pat. No. 6,446,708 (Japan Utility Model Registration No. 3,085,340) discloses one example of a heat sink which can be employed for the technology of this kind. A heat sink of this kind is provided with two extending portions extending diagonally in an upward direction as if the wings are spreading above a body portion of the base, onto which a heat-emitting element is to be mounted. A plurality of radiation fins, extending in either of an upward direction or a downward direction, are integrally provided at either of an upper end portion or a lower end portion of the two extending portions. The plurality of radiation fins are divided into a plurality of strips, and end portions of the plurality of strips extending from lower end portions of the extending portions in the downward direction are connected with each other.
In the conventionally proposed heat sinks, heat which has been transferred from a heat-emitting element to a body portion of a base is not radiated immediately after transferred. The heat is radiated after the heat has been transferred to the plurality of strips provided at each of the extending portions. When each of the radiation fins is divided into the plurality of strips, heat radiation efficiency seems to be improved. However, since the total cross sectional area of heat passages where the heat passes decreases, the heat radiation efficiency is lowered. Furthermore the plurality of strips provided at each of the lower end portions of the two extending portions extend straight in a downward direction. The end portions of the strips are connected with each other. Therefore the heat passages, where the heat passes from the heat-emitting element to the end portions of the plurality of strips provided at the lower end portions of the extending portions, are lengthened. Also components located in a vicinity of the heat-emitting element are more readily heated, due to radiant heat which is radiated from the plurality of strips provided at the lower end portions of the extending portions. There has been a limit, due to its construction, for enhancing cooling efficiency in the cooling apparatus which has been conventionally proposed, even though the heat sink is arranged in the air channel for cooling.